Synthetic Layered Magnesium Silicates and Their Derivatives for High Performance Oil-based Drilling Fluids

ABSTRACT

A method of producing a synthetic functionalized additive including the steps of mixing an amount of a magnesium salt with a fluid medium to produce a magnesium-containing fluid, adding an amount of a silane to the magnesium-containing fluid to produce a reactant mix, adding an amount of an aqueous hydroxide to the reactant mix to produce a reaction mixture, mixing the reaction mixture for a mix period, refluxing the reaction mixture for a reflux period to produce a product mix, treating the product mix to separate the synthetic functionalized additive.

RELATED APPLICATIONS

This application claims priority from U.S. Non-Provisional patentapplication Ser. No. 16/560,659 filed on Sep. 4, 2019, which claimspriority from U.S. Provisional Patent Application No. 62/726,512 filedon Sep. 4, 2018. For purposes of United States patent practice, thisapplication incorporates the contents of both the Provisional PatentApplication and the Non-Provisional Patent Application by reference intheir entirety.

TECHNICAL FIELD

Disclosed are compositions and methods for use as fluid additives.Specifically, disclosed are compositions and methods for enhancingrheological properties of drilling fluids in a downhole environment.

BACKGROUND

Organically modified smectitic materials, such as bentonite and othermontmorillonites, and hectorites can be utilized as viscosifiers indrilling fluids. These materials are composed of layered inorganicmaterials, such as alumino-silicates and magnesium silicates. Organicmodifiers, such as aliphatic and aromatic quaternary ammonium salts, inthese viscosifiers are linked with ionic interaction on the surface ofthe layered inorganic materials, see FIG. 1. These weak interactionsbetween organic moieties and the layered inorganic materials aresusceptible to failure under high temperatures, such as temperatures upto 500 degrees Fahrenheit (° F.), high pressures, such as pressures upto 35,000 pounds per square inch (psi), shearing stresses, and repeatedexposure to alkaline or acidic conditions.

The ionic interactions are indicated by plus signs and minus signs. Asshown in FIG. 1, when the weak interactions fail the layers break apart.A failure of the interaction between the organic moieties and thelayered inorganic materials negates the intended effectiveness of thematerial in its application.

Additionally, traditional viscosifiers are primarily obtained fromnatural resources. As a result, the chemical composition of theviscosifiers changes from batch to batch. The changes from batch tobatch require frequent optimization of drilling fluids formulationsduring one drilling operation.

SUMMARY

Disclosed are compositions and methods for use as fluid additives.Specifically, disclosed are compositions and methods for enhancingrheological properties of drilling fluids in a downhole environment.

In a first aspect, a method of producing a synthetic functionalizedadditive is provided. The method includes the steps of mixing an amountof a magnesium salt with a fluid medium to produce amagnesium-containing fluid, adding an amount of a silane to themagnesium-containing fluid to produce a reactant mix, adding an amountof an aqueous hydroxide to the reactant mix to produce a reactionmixture, mixing the reaction mixture for a mix period, refluxing thereaction mixture for a reflux period to produce a product mix, treatingthe product mix to separate the synthetic functionalized additive.

In certain aspects, the magnesium salt is selected from the groupconsisting of magnesium chloride, magnesium chloride hydrates, magnesiumnitrate, magnesium nitrate hydrates, magnesium bromide, magnesiumbromide hexahydrate, and combinations of the same. In certain aspects,the amount of the magnesium salt is between 3 percent by weight (% bywt) and 15% by wt of the fluid medium. In certain aspects, the fluidmedium is selected from the group consisting of water, an alcohol, andcombinations of the same. In certain aspects, the silane is selectedfrom the group consisting of phenyltrimethoxysilane,trimethoxy(propyl)silane, trimethoxymethylsilane,hexadecyltrimethoxysilane, octyltriethoxysilane, tetraethylorthosilicate, N-[3-(trimethoxysilyl)propyl]ethylenediamine,(3-aminopropyl)triethoxysilane, and combinations of the same. In certainaspects, the amount of the silane is between 3% by wt and 12% by wt ofthe fluid medium, such that a molar ratio of silicone to magnesium inthe synthetic functionalized additive is in a range between 0.7 and 1.5.In certain aspects, the aqueous hydroxide includes a hydroxide, thehydroxide selected from the group consisting of sodium hydroxide,potassium hydroxide, ammonium hydroxide, and combinations of the same.In certain aspects, the amount of the aqueous hydroxide is added to thereactant mix to achieve a target pH of the reaction mixture, where thetarget pH is between 7 and 12. In certain aspects, the mix period isbetween one hour and seventy-two hours. In certain aspects, thesynthetic functionalized additive includes a synthetic layered magnesiumsilicate and a functional group. In certain aspects, the functionalgroup is selected from the group consisting of hydroxyl groups (—OH),saturated alkyl groups having the formula (—CH₂(CH₂)_(x)CH₃), where x isan integer between 0 and 18, phenyl groups, amine groups, diaminegroups, carboxylate groups, amide groups, acrylate groups, thiol groups,methacrylate groups, isocyanate groups, and combinations of the same. Incertain aspects, the step of treating the product mix to separate thesynthetic functionalized additive includes the steps of reducing thetemperature of the product mix, separating solids in the product mixfrom a liquid in the product mix in a solids separator, and drying thesolids separated in the solids separator to produce the syntheticfunctionalized additive.

In a second aspect, a composition of a synthetic functionalized additiveis provided. The composition includes a synthetic layered magnesiumsilicate that includes a first functionalized silicate layer thatincludes a tetrahedral silicate layer and a functional group. Thesynthetic layered magnesium silicate further includes an octahedralbrucite layer that includes magnesium oxide/hydroxide. The syntheticlayered magnesium silicate further includes a second functionalizedsilicate layer that includes the tetrahedral silicate layer and thefunctional group. The octahedral brucite layer is positioned between thefirst functionalized silicate layer and the second functionalizedsilicate layer. The composition further includes the functional groupcovalently bonded to the tetrahedral silicate layer of the firstfunctionalized silicate layer and separately covalently bonded to thetetrahedral silicate layer of the second functionalized silicate layer,where the functional group extends from both the first functionalizedsilicate layer and the second functionalized silicate layer away fromthe octahedral brucite layer.

In certain aspects, a thickness of the synthetic layered magnesiumsilicate is 1 nanometer and a lateral dimension of the synthetic layeredmagnesium silicate is between 2 nanometers (nm) and 5 microns.

In a third aspect, a method of using a synthetic functionalized additivein a well fluid is provided. The method includes the steps of preparinga well fluid, where the well fluid is selected from an aqueous-basedfluid, oil-based fluid, and combinations of the same, adding an amountof the synthetic functionalized additive to the well fluid to produce arheologically-modified well fluid, subjecting the rheologically-modifiedwell fluid to a shear stress, and injecting the rheologically-modifiedwell fluid into a well.

In certain aspects, the amount of the synthetic functionalized additivein the rheologically-modified well fluid is between 0.1 percent ofweight in the total volume (% w/v) to 20% w/v. In certain aspects, therheologically-modified well fluid is operable to exhibitrheologically-independent behavior.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the scope willbecome better understood with regard to the following descriptions,claims, and accompanying drawings. It is to be noted, however, that thedrawings illustrate only several embodiments and are therefore not to beconsidered limiting of the scope as it can admit to other equallyeffective embodiments.

FIG. 1 provides a pictorial representation of organic modifiers attachedto a traditional viscosifier through labile electrostatic interaction.

FIG. 2 provides a pictorial representation of a synthetic functionalizedadditive showing the synthetic layered magnesium silicate withcovalently-linked organic functional groups.

FIG. 3 is a graph of the results of the electrical stability test ofExample 2.

FIG. 4A is graphs of the results of Example 2 of the low shear dialreadings versus speed at different temperatures.

FIG. 4B is graphs of the results of Example 2 of the low shear dialreadings versus speed at different temperatures.

FIG. 4C is a graph of the results of Example 2 of the low shear dialreadings versus speed at different temperatures.

FIG. 5 is a graph of the results showing plastic viscosity at differenttemperatures for Example 2.

FIG. 6 is a graph of the results showing apparent viscosity at differenttemperatures for Example 2.

FIG. 7 is a graph of the results showing yield point at differenttemperatures for Example 2.

In the accompanying Figures, similar components or features, or both,may have a similar reference label.

DETAILED DESCRIPTION

While the scope of the composition and method will be described withseveral embodiments, it is understood that one of ordinary skill in therelevant art will appreciate that many examples, variations andalterations to the composition and methods described here are within thescope and spirit of the disclosure.

Accordingly, the embodiments described are set forth without any loss ofgenerality, and without imposing limitations, on the disclosure. Thoseof skill in the art understand that the scope includes all possiblecombinations and uses of particular features described in thespecification.

The compositions and methods are directed to synthetic functionalizedadditives. The synthetic functionalized additives can be used indrilling fluids. The synthetic functionalized additives can includeorganic functional groups covalently bonded to synthetic layeredmagnesium silicate. The methods include making the synthetic layeredmagnesium silicate and preparing the synthetic functionalized additives.The synthetic layered magnesium silicates are polycrystalline materialsand not single crystals.

Advantageously, the synthetic functional additives contain strongcovalent bonds between the organic functional groups and the syntheticlayered magnesium silicate which reduce the effects of stresses on thebonds meaning more bonds remain intact during a treatment process. Withmore bonds remaining intact, the covalent bonds increase theeffectiveness of the synthetic functional additives. Advantageously, thesynthetic layered magnesium silicates can be reproduced resulting inconsistent composition from batch to batch. Consistent and reproducibleresults is an advantage over naturally-derived materials, such asorganoclays or organically modified layered materials, which are subjectto the impurities in the natural source. Additionally, the synthesis canbe manipulated to produce certain results in the product, such aschanging the crystallinity. Advantageously, the synthetic layeredmagnesium silicates provide consistency for the duration of anapplication and reduce or eliminate the need to alter the formulationduring use and application. Advantageously, the synthetic functionaladditives can be prepared in one-pot synthesis approaches reproducibleat industrial-scale. Advantageously, fluids containing the syntheticfunctional additives exhibit rheologically-independent behavior atpressures up to 35,000 psi and temperatures up to 500° F., which isadvantageous because having rheologically-independent behavior means thefluids maintain their properties, such as viscosity and thixotropy, inthe face of an applied stress and changes to the temperature. Fluidscontaining the synthetic functional additives are less susceptible tostresses than fluids that do not exhibit rheologically-independentbehavior. Advantageously, fluids containing the synthetic functionaladditives exhibit less change in viscosity due to variation intemperature as compared to the same fluids containing conventionalrheology modifiers, such as organoclays. Advantageously, fluidscontaining the synthetic functional additives exhibit reductions infriction factor as compared to the same fluids containing conventionalrheology modifiers, such as organoclays. Advantageously, the syntheticfunctional additives contain organophilic and hydrophilicfunctionalities.

As used throughout, “brucite” refers to a magnesium oxide/hydroxidehaving monomeric formula MgO(OH)₂.

As used throughout, “octahedral” refers to the crystal pattern definingan octahedron, with eight triangular faces, twelve straight edges, andsix vertices.

As used throughout, “tetrahedral” refers to the crystal pattern defininga tetrahedron, with four triangular faces, six straight edges, and fourvertices.

As used throughout, “silane” refers to a silicon compound containing atleast three alkoxy groups (an alkyl group bonded to oxygen), where the4^(th) substituent includes a functional group and can be a 4^(th)alkyoxy group or can be a carbon containing compound.

As used throughout, “viscosifier,” “viscosity modifier,” and“rheological modifier” refer to compounds that change rheologicalproperties when added to a fluid. Primarily, viscosifiers are used toincrease the viscosity of a fluid.

As used throughout, “thixotropic” refers to the tendency of a fluid orgel to exhibit a decrease in viscosity when a stress or a change intemperature is applied, such as mixing, shaking, shearing, or agitating.This property is time-dependent. Thixotropic control additives areadditives that can minimize the decrease in viscosity of a fluid when astress or a change in temperature is applied.

As used throughout, “suspension additives” refers to additives that canreduce settling of solid particles in fluids or gels.

As used throughout, “rheologically-independent behavior” refers to afluid where the changes in rheological properties, such as viscosity andthixotropy, experience less than 10 percent (%) change due to avariation in an applied stress. Stresses can include shear stress,temperature, and combinations of the same. For example, an appliedstress can be a rate of mixing and a variation in that applied stresswould occur when the rate of mixing is being increased or decreased. Anexample of a fluid that exhibits rheologically-independent behavior is afluid that does not experience a change in viscosity due to a variationin the temperature. An example of rheologically-independent behavior canbe seen in FIG. 4C, where sample 1 of Example 2 exhibits minimal changein the dial reading over an increase in the RPM's at 300° F.

As used throughout, “talc” refers to a natural mineral composed ofmagnesium silicates formed naturally over thousands of years and iscrystalline. Talc does not include organic functional groups.

The synthetic functionalized additive includes a synthetic layeredmagnesium silicate and a functional group. The synthetic layeredmagnesium silicate can have a thickness of about 1 nanometer (nm) and alateral dimension in the range from 2 nanometers (nm) to 5 microns. Theoverall thickness of the synthetic functionalized additive can depend onthe length of the functional groups.

The synthetic layered magnesium silicate includes a layer of octahedralbrucite positioned between two functionalized silicate layers.

The layer of octahedral brucite can be synthesized as part of theprocess or can be obtained from other sources. The octahedral brucitelayer can be synthesized by reacting a magnesium salt with an aqueoushydroxide. Any magnesium salt that can react with a hydroxide can beused. Examples of the magnesium salt can include magnesium chloride,magnesium chloride hydrates, magnesium nitrate, magnesium nitratehydrates, magnesium bromide, magnesium bromide hexahydrate, andcombinations of the same. Magnesium chloride hydrates have the chemicalformula MgCl₂(H₂O)_(x), where x is selected from 2, 4, 6, 8, and 12.Magnesium nitrate hydrates have the chemical formula Mg(NO₃)₂(H₂O)_(y),where y is selected from 2 and 6. Other sources of octahedral brucitecan include magnesium-rich bittern brine, a byproduct of sodium chlorideproduction from sea water.

The aqueous hydroxide can include a hydroxide in water. The hydroxidecan be present in an amount between 2% by wt and 10% by wt, alternatelybetween 2% by wt and 8% by wt. The hydroxide can be any hydroxide thatcan react with a salt. Examples of the hydroxide include sodiumhydroxide, potassium hydroxide, ammonium hydroxide, and combinations ofthe same.

Each of the functionalized silicate layers contains a tetrahedralsilicate layer and a functional group. The functional groups arecovalently bonded to the tetrahedral silicate layer. The functionalizedsilicate layers can be obtained by reacting the octahedral brucite witha silane. Any silane containing a functional group and capable offorming a tetrahedral layer can be used. The silanes can be available asan aqueous solution, a non-aqueous solution, or a liquid. Examples ofsilanes for use in the synthetic layered magnesium silicate includephenyltrimethoxysilane [C₆HsSi(OCH₃)₃], trimethoxy(propyl)silane[CH₃CH₂CH₂Si(OCH₃)₃], trimethoxymethylsilane [CH₃Si(OCH₃)₃],hexadecyltrimethoxysilane [CH₃(CH₂)₁₅Si(OCH₃)₃], octyltriethoxysilane[CH₃(CH₂)₇Si(OCH₃)₃], tetraethyl orthosilicate [Si(OC₂H₅)₄],N-[3-(trimethoxysilyl)propyl]ethylenediamine[NH₂(CH₂)NH(CH₂)₃Si(OCH₃)₃], (3-aminopropyl)triethoxysilane[NH₂(CH₂)₃Si(OCH₃)₃], silanes having the formula RSi(OR″)₃, andcombinations of the same. Where silanes have the formula RSi(OR″)₃, R″can include a methyl group (—CH₃), an ethyl group (—C₂H₅), andcombinations of the same; and R can include alkyl groups, aryl groups,and combinations of the same. Alkyl groups can include alkyl groupshaving saturated groups, alkyl groups having unsaturated groups, alkylgroups having functional substituents, and combinations of the same.Aryl groups can include aryl groups having saturated groups, aryl groupshaving unsaturated groups, aryl groups having functional substituents,and combinations of the same. The functional substituents can includeamines, carboxylates, amides, acrylates, thiols, hydroxyls, isocyanates,methacrylates and combinations of the same. The functional substituentscan be attached at the end of the chain, can be attached in-between, andcombinations of the same. The functional substituents form functionalgroups of the silane. In at least one embodiment, the silanes for use inthe synthetic layered magnesium silicate include phenyltrimethoxysilane,trimethoxy(propyl)silane, trimethoxymethylsilane,hexadecyltrimethoxysilane, octyltriethoxysilane, tetraethylorthosilicate, N-[3-(trimethoxysilyl)propyl]ethylenediamine,(3-aminopropyl)triethoxysilane, and combinations of the same. In atleast one embodiment, the silane has the formula RSi(OR″)₃.

The silane can be selected based on the desired functional group. Thefunctional groups can include hydroxyl groups (—OH), saturated alkylgroups having the formula (—CH₂(CH₂)_(x)CH₃), x is an integer between 0and 18, phenyl groups, amine groups, diamine groups, carboxylate groups,amide groups, acrylate groups, thiol groups, methacrylate groups,isocyanate groups, and combinations of the same. Table 1 lists thefunctional group resulting from each silane.

TABLE 1 Examples of silanes and the corresponding functional groupSilane Functional Group phenyltrimethoxysilane Phenyl group, —C₆H₅trimethoxy(propyl)silane Saturated alkyl group, —CH₂(CH₂)CH₃trimethoxymethylsilane Methyl group, —CH₃ hexadecyltrimethoxysilaneSaturated alkyl group, —CH₂(CH₂)₁₄CH₃ octyltriethoxysilane Saturatedalkyl group, —CH₂(CH₂)₆CH₃ tetraethyl orthosilicate —OC₂H₅N-[3-(trimethoxysilyl)propyl]ethyl- Diamine group, enediamine—(CH₂)₃NH(CH₂)₂NH₂ (3-aminopropyl)triethoxysilane Amine group,—(CH₂)₃NH₂ RSi(OR″)₃ R″ is a methyl group (—CH₃), an ethyl group(—C₂H₅), and combinations of the same; and R is an alkyl group, an arylgroup, and combinations of the same.

Producing the functionalized silicate layer from a silane that containsthe desired functional group results in a synthetic functionalizedadditive where the functional group is covalently bonded to thetetrahedral silicate layer of the synthetic layered magnesium silicate.

Referring to FIG. 2 an embodiment of a functionalized silicate additiveis provided. Octahedral brucite layer 10 is sandwiched between twotetrahedral silicate layers 20. Functional groups 30 are covalentlybonded to tetrahedral silicate layer 20. As functional groups 30 extendfrom tetrahedral silicate layer 20 away from octahedral brucite layer10, functional groups 30 serve to separate the synthetic layeredmagnesium silicate 40.

References to “a functional group” should be interpreted to includemultiple instances a type of functional group bonded to the tetrahedralsilicate layer and alternately multiple instances of multiple types offunctional groups bonded to the tetrahedral silicate layer.

The synthetic layered magnesium silicate is in the absence of talc. Thesynthetic layered magnesium silicates differ from talc in at least thefollowing ways: (a) the synthetic layered magnesium silicates includeorganic functionalities, unlike talc which does not; (b) the syntheticlayered magnesium silicates are partially crystalline; (c) the syntheticlayered magnesium silicates contain covalently linked organicfunctionalities resulting in chemically strong bonding in contrast talc,even organically modified talc, has physically linked organicfunctionalities resulting in weak bonding; and (d) the structure of thesynthetic layered magnesium silicates can be controlled during thesynthesis process, whereas the structure of talc cannot be modified fromthe natural development.

A method of producing or synthesizing the synthetic functionalizedadditive is provided.

In a first step, an amount of the magnesium salt is mixed with a fluidmedium to produce a magnesium containing fluid. Any fluid mediumsuitable for suspending a metal oxide or metal hydroxide reaction. Thefluid medium can include water, an alcohol, and combinations of thesame. Examples of the alcohol can include methanol, ethanol, propanol,butanol, and combinations of the same. The amount of magnesium salt canbe in the range from between about 3% by wt of the fluid medium andabout 15% by wt of the fluid medium and alternately in the range frombetween about 5% by wt of the fluid medium and about 7% by wt of thefluid medium.

An amount of the silane can be added to the magnesium-containing fluidto produce a reactant mix. The amount of silane added can be betweenabout 3% by wt of the fluid medium and about 12% by wt of the fluidmedium and alternately between about 4% by wt of the fluid medium andabout 6% by wt of the fluid medium. The amount of silane added can bedetermined to maintain a silicone to magnesium molar ratio in thesynthetic layered magnesium silicate of between about 0.7 and about 1.5,alternately between about 0.8 and about 1.4, alternately between about 1and about 1.4. In at least one embodiment, the amount of silane addedresults in a silicone to magnesium molar ratio in the synthetic layeredmagnesium silicate of 1.33.

Adding the amount of the silane to the magnesium-containing fluid isimportant to produce a synthetic functionalized additive having thelayered structure. A change in the order of mixing, by adding themagnesium salt to the silane produces amorphous materials that do notpossess the layered structure required of the synthetic functionalizedadditive.

An amount of aqueous hydroxide can be added to the reactant mix toproduce the reaction mixture. The amount of aqueous hydroxide added canadjust the pH of the reactant mix. The amount of aqueous hydroxide canbe added to the reactant mix to reach a target pH of the reactionmixture. The target pH of the reaction mixture can be between about 7and about 12, and alternately between about 9 and about 10.

Each of the addition steps can be performed at a temperature in therange between about 20 degrees Celsius (° C.) and about 30° C. andalternately at a temperature of about 25° C. Each of the addition stepscan be performed at ambient pressure. The reaction mixture can beprepared in one reaction vessel. The reaction vessel can be fitted witha stirring mechanism such that the mixture is constantly stirred duringthe addition steps. Each addition step can be followed by a period ofmixing. The reaction vessel can be fitted with a condenser. The reactionvessel can be configured for hydrothermal reaction, where the reactionmixture can be maintained at a pressure at the reflux conditions.

The reaction mixture can be mixed for a mixing period. The mixing periodcan be at least 30 minutes, alternately at least one hour, alternatelybetween one hour and seventy-two hours, alternately between 12 hours and72 hours, alternately between 24 hours and 48 hours, alternately betweenfour hours and eight hours, alternately between five hours and sevenhours, and alternately between five hours and six hours. Mixing thereaction mixture under an alkaline condition can enable the formation ofbrucite and the subsequent hydrolysis of the silanes.

Following the mixing period, the reaction mixture can be refluxed in thereaction vessel for a reflux period to produce the product mix. Thereflux period can be greater than 1 hour, alternately greater than 5hours, alternately greater than 10 hours, alternately greater than 24hours, alternately between 24 hours and 72 hours, alternately between 24hours and 48 hours. During the reflux period, the temperature in thereaction vessel can be increased to the refluxing condition. Therefluxing condition can be the boiling point of the reaction mixture.The refluxing condition can be in the range between 50° C. and 80° C. Ascomponents boil, they can enter the condenser fitted onto the reactionvessel. The refluxing condition allows the reaction of silanes to formthe tetrahedral silicate layer on either side of the layer of octahedralbrucite, resulting in the functionalized synthetic additive.

The formation of the layer of octahedral brucite can begin upon additionof the aqueous hydroxide. Hydrolysis of the silanes can begin uponaddition of the aqueous hydroxide. The condensation reactions of thesilanes can begin when the temperature in the reaction mixture isincreased to the refluxing condition. The condensation reactions of thesilanes continues for the reflux period. The functionalized silicatelayers form on the layer of octahedral brucite during the reflux period.

Following the refluxing step, the product mix can be subjected to one ormore treatment operations to separate the solid synthetic functionalizedmagnesium silicate from the mother liquids in the product mix. Thetreatment operations can include reducing the temperature of the productmix, separating the solid synthetic functionalized magnesium silicate,washing the separated solids, and drying the solids under vacuum.Separating the solid synthetic functionalized magnesium silicate can beperformed using any separation unit capable of separating solids fromliquids. Examples of separation units suitable for separating solidsfrom liquids include filtration and centrifuging. The separated solidscan be washed with de-ionized water. Drying under vacuum can be done atelevated temperatures or at room temperature.

The length of the reflux period can influence the crystallinity of thesynthetic layered magnesium silicates. Hydrothermal reaction during thereflux period can allow crystallization and growth in the lateraldimension. The longer the reflux period the greater the size of thelateral dimension. The reflux conditions can also improve thecrystallinity of the functionalized silicate layers. The condensationreactions of the silanes involve the removal of water molecules from theedges of the inorganic layer of octahedral brucite and the hydrolysisproducts of silanes, a longer reflux period provides more time for thesereactions resulting in improved crystallinity.

Advantageously, synthesizing the synthetic layered magnesium silicateallows the physical properties of the synthetic layered magnesiumsilicate to be tailored to meet desired specifications. Examples of thephysical properties that can be tailored include the crystallinity, theorganic moieties, the lateral dimensions, and combinations of the same.The crystallinity of the synthetic layered magnesium silicate can betailored to possess low crystallinity, moderate crystallinity, or highcrystallinity. The organic moieties can be tailored to includehydrophobic organic moieties, hydrophilic organic moieties, and acombination of the same. The lateral dimensions, such as the length,height and width, can be modified by increasing the reaction time.Tailoring the physical properties changes the thixotropic behavior, theviscosity of the well fluids, and combinations of the same. In at leastone embodiment, tailoring the physical properties ensures the syntheticlayered magnesium silicate contains enough structure to providestability and viscosity in the well fluids.

The method of producing the synthetic functionalized additive is in theabsence of step of grafting the organic moieties. Advantageously, themethod of producing the synthetic functionalized additive provides amethod for in-situ formation, which results in covalently linked siliconto oxide (Si—O) bonds. Covalently linked Si—O bonds have increasedstructural integrity exhibiting reduced likelihood of detachment of theorganic moieties.

The synthetic functionalized additive can be used as a viscosifier, athixotropic control additive, a suspension additive, a nucleating agentadditive, and a release rate control additive. The syntheticfunctionalized additives can be used as additives in well fluids,paints, inks, cosmetic formulations, personal care formulations,synthesis of nanocomposites from thermoplastic or thermosettingpolymers, and therapeutic formulations (sustained release). Well fluidscan include drilling fluids, packer fluids, lost circulation fluids,production fluids, and combinations of the same. The well fluid can bean aqueous-based fluid, an oil-based fluid, or combinations of the same.In general, the synthetic functionalized additives can be used in placeof organophilic nanosilicas.

In at least one embodiment the synthetic functionalized additive can bemixed with a well fluid as a viscosifier to produce arheologically-modified well fluid. The amount of syntheticfunctionalized additive added to the well fluid can be between 1 gramand 3 grams and alternately between 1.5 grams and 2.5 grams. In at leastone embodiment the synthetic functionalized additive in the well fluidis 2 grams. The amount of synthetic functionalized additive in therheologically-modified well fluid can be in an amount between 0.1% w/vand 20% w/v, alternately 0.5% w/v and 5% w/v, alternately between 1% w/vand 4% w/v, alternately between 1.5% w/v and 3.5% w/v. In at least oneembodiment the amount of the synthetic functionalized additive is 2%w/v. For example purposes only, a 0.1% w/v rheologically-modified wellfluid can contain 0.1 grams of the synthetic functionalized additive in99.9 mL of the well fluid. For example purposes only, a 20% w/vrheologically-modified well fluid can contain 20 g of the syntheticfunctionalized additive in 80 mL of the well fluid. Therheologically-modified well fluid can be injected into a well.

In at least one embodiment, the synthetic functionalized additive isused as an additive in paint compositions. Additives in paintcompositions can include thixotropic agents, dispersants, andanti-settling agents. The synthetic functionalized additive can be usedas one or more of these additives. The synthetic functionalized additivecan be added to improve the stability of the paint composition or can beadded to improve the application of the paint. The syntheticfunctionalized additive can improve the stability of the paint byincreasing the length of time over which the solid particles remainsuspended in the paint fluids and can increase the gel strength of thepaint. The synthetic functionalized additive can be added as ananti-settling agent to reduce separation of the vehicle, also known asthe binder including any diluent, from the solids, such as pigments. Byreducing solids settling, the synthetic functionalized additive canincrease the shelf-life of a paint composition. The longer theshelf-life of a paint composition, the more stable the paintcomposition. In an alternate embodiment, the synthetic functionalizedadditive can be used as an additive to impart hydrophobicity to thepaint surface improving protection against moisture and water.

In at least one embodiment, the paint composition is a paint dispersionincluding the synthetic functionalized additive, a binder, and apigment. The paint composition can further include resins, solvents,solid particles of metal oxides, clay minerals, and combinations of thesame. The weight ratio of the synthetic functionalized additive to thebinder is between 0.001 to 0.2 on a dry basis. The binder can be anacrylate-based binder or a latex-based binder. In a first step ofproducing the paint composition, the pigments can be mixed with thesynthetic functionalized additive and any other additives to beincorporated in the paint composition, to produce a particle mix. Theparticle mix can then be mixed an amount of resins or solvents toproduce a non-binding liquid. This is known as the mill-base stage. Thenon-binding liquid can then be mixed with the binder, such that thepigment disperses in the binder producing the paint composition. This isknown as the let-down stage. Additional solvents, resins, and additivescan be added during the let-down stage to achieve the desired propertiesof the paint composition, such as the color, sheen, drying time,consistency, and durability.

In at least one embodiment, the synthetic functionalized additive isused in cosmetic compositions as an emulsifying agent. Emulsifyingagents can be used in cosmetic compositions to produce and maintainemulsions. The synthetic functionalized additive can be used inoil-in-water (O/W) emulsions, water-in-oil (W/O) emulsions, or multipleemulsions. In at least one embodiment, the cosmetic composition can bean O/W emulsion containing the synthetic layered magnesium silicate inthe range between 0.1 wt % to 10 wt % of the O/W emulsion. The cosmeticcomposition can be produced by separately prepare the oil phase and thewater phase. The purpose and desired properties of the cosmeticcomposition can dictate to which phase different ingredients are added.The synthetic functionalized additive can serve as a thickening agent,an emulsifier or a stabilizer. Other ingredients can include perfumes,color, and preservatives. The prepared oil phase and water phase can bemixed to form an emulsion. Mixing can continue until the emulsion ishomogeneous. In certain embodiments, the mixing step can be performed atelevated temperature. The elevated temperature can be between 45° C. and85° C.

In at least one embodiment, the synthetic functionalized additive isused as a viscosifier for oleophilic personal care formulations. In atleast one embodiment, the synthetic functionalized additive is used toremove oil from water. In at least one embodiment, the syntheticfunctionalized additive is used as a nucleating agent additive forpolymers.

EXAMPLES Example 1

Example 1 includes a process to produce a synthetic functionalizedadditive. First, the magnesium-containing fluid was prepared bydissolving 15.0 grams (g) of the magnesium salt, magnesium chloridehexahydrate, in 300 mililiters (mL) of methanol, as the fluid medium, toproduce the magnesium-containing fluid. Next, 18.3 mL ofphenyltrimethoxysilane, as the silane, was added to themagnesium-containing fluid at room temperature, while stirring, toproduce the reactant mix. The aqueous hydroxide was produced bydissolving 5.9 g of sodium hydroxide in 100 mL of de-ionized water. Theaqueous hydroxide was added to the reactant mix at room temperature withcontinuous stirring over a period of 30 minutes (min) to produce thereaction mixture. The reaction mixture was a milky white suspension. Thereaction mixture was stirred at room temperature for 5 hours. Followingthe mix time, the reaction mixture was refluxed at 70° C. for 48 hours.The refluxing apparatus included a stirring facility and a condenser,where cold water is circulated in the condenser during the refluxingstep. Following the refluxing step, the product mix was cooled to atemperature between 35° C. and 40° C., filtered, washed three times with100 mL of de-ionized water, and dried under vacuum at a temperature of80° C. In total, 17.5 g of the synthetic functionalized additive wasrecovered. The synthetic functionalized additive of Example 1 waslabeled MagSil-Phenyl.

The reaction in Example 1 occurred according to the following reaction:

The functional group was a phenyl group.

Example 2

Example 2 was a comparison study of rheological properties of acommercial viscosifier, Geltone V® available from Halliburton (Houston,Tex.), to different samples of synthetic functionalized additive in adrilling fluid. The synthetic functionalized additives wereMagSil-Phenyl, MagSil-C17, and MagSil-C3. MagSil-Phenyl was thesynthetic functionalized additive of Example 1. MagSil-C17 was preparedwith hexadecyltrimethoxysilane as the silane following a similarprocedure as described in Example 1. MagSil-C3 was prepared withtrimethoxy(propyl)silane as the silane following a similar procedure asdescribed in Example 1. A drilling fluid having the composition of Table1 was prepared according to the following method.

TABLE 1 Formulation of Oil-Based Drilling Fluid Amount Component (g)Diesel 192 Emulsifier¹ 8 Surfactant² 4 Lime 6 Polymer³ 2 De-ionizedWater 22.48 Saturated CaCl₂ brine 53.27 Filtration Control Resin⁴ 4Weighting material (Barite) 209 Total Weight 500.75 ¹VERSAMUL ®available from MiSWACO (Houston, TX) ²VERSACOAT ™ available from MiSWACO(Houston, TX) ³Priamine ™ 1074 available from Croda International (ChinoHills, CA) ⁴VERSATROL ® HT available from MiSWACO (Houston, TX)

In a first step, 2 g of the viscosifier was added to the diesel andmixed for 1-2 minutes. Then, the VERSAMUL®, VERSACOAT™, lime, andPriamine™ 1074 were added in succession, with 1-2 minutes of mixing inbetween each addition. The mixture was subjected to a shear stress for20 minutes. Following the shear stress, a solution of the calciumchloride brine in the de-ionized water was added to the mixture followedby 1-2 minutes of mixing. Then, the VERSATROL® HT was added followed byshear stress for 20 minutes. Next, the barite was added followed byshear stress for 20 minutes.

The specific gravity of each viscosifier sample was measured and isshown in Table 2.

TABLE 2 Specific gravity of each viscosifier sample Sample ViscosifierSpecific Gravity Sample 1 MagSil-Phenyl 1.5 Sample 2 MagSil-C17 1.6Sample 3 MagSil-C3 1.8 Sample 4 Geltone V 1.6

Finally, 20 g of Rev Dust™, a calcium montmorillonite, available fromNewpark Drilling Fluids (Katy, Tex.) was added followed by shear stressfor 5 minutes. The Rev Dust was added to simulate cuttings during adrilling process. After the final shear stress application, the entiremixture was aged by hot rolling the drilling fluid at 275° F. under 500pounds per square inch (psi) pressure in a pressure vessel.

The electrical stability (ES) of each sample was measured before andafter aging using an electrical stability tester from the FannInstrument Company. The results are shown in FIG. 3. FIG. 3 indicatesthat the electrical stability of Samples 1-3 with the syntheticfunctionalized additives are comparable to Sample 4 with the commercialviscosifier. The greater the ES value, the greater the indication of astable inverted emulsions. The stable inverted emulsion was composed ofa brine-in-diesel system. The synthetic functionalized additivesincrease the viscosity in the continuous (diesel) phase and thereforestabilized droplets of brine in the diesel. The stabilized droplets ofbrine separated in the diesel phase results in a greater ES valueobserved. A lower ES means the continuous (diesel) phase does not havesufficient viscosity to separate each droplet of brine.

Rheological properties of Samples 1, 2 and 4, including plasticviscosity, apparent viscosity, and yield point, were measured underpressure of 10,000 psi at different temperatures, 150° F., 200° F., 250°F., 275° F., and 300° F. The measurements were performed using arheometer from the Fann Instrument Company. The raw results showing thelow shear dial readings at different RPM's for each temperature areshown in FIGS. 4A-4C. The results show that rheologically-independentbehavior can be achieved using the synthetic functionalized additives atdifferent temperatures under 10,000 psi pressure. The results suggestdrilling fluids with the synthetic functionalized additive would besuitable for use at wellbore temperatures and pressures. For example, at200° F., Sample 1 exhibits only a small increase in dial reading from200 RPM to 600 RPM. In contrast, Sample 4 exhibits a greater increase(about 20) from 200 RPM to 600 RPM. Moreover, the results illustratethat the functional groups remain covalently bonded to the syntheticlayered magnesium silicate and do not detach.

The results for plastic viscosity, apparent viscosity, and yield pointare described with reference to FIGS. 5-7. In FIG. 5, the plasticviscosity (PV) on the y-axis is a measure of the dial reading at 600revolutions per minute (RPM) minus the dial reading at 300 RPM. In FIG.6, the apparent viscosity (AV) on the y-axis is a measure of the dialreading at 600 RPM divided in half. In FIG. 7, the yield point on they-axis is a measure of the dial reading at 300 RPM minus the PV. Therheological properties can be used to develop a drilling fluid for aspecific wellbore application, thus knowing the rheological propertiesis valuable to producing application specific drilling fluids.

Although the embodiments have been described in detail, it should beunderstood that various changes, substitutions, and alterations can bemade hereupon without departing from the principle and scope.Accordingly, the scope of the embodiments should be determined by thefollowing claims and their appropriate legal equivalents.

There various elements described can be used in combination with allother elements described here unless otherwise indicated.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise.

Optional or optionally means that the subsequently described event orcircumstances may or may not occur. The description includes instanceswhere the event or circumstance occurs and instances where it does notoccur.

Ranges may be expressed here as from about one particular value to aboutanother particular value and are inclusive unless otherwise indicated.When such a range is expressed, it is to be understood that anotherembodiment is from the one particular value to the other particularvalue, along with all combinations within said range.

As used here and in the appended claims, the words “comprise,” “has,”and “include” and all grammatical variations thereof are each intendedto have an open, non-limiting meaning that does not exclude additionalelements or steps.

That which is claimed is:
 1. A composition of a synthetic functionalizedadditive, the composition comprising: a synthetic layered magnesiumsilicate, the synthetic layered magnesium silicate comprising: a firstfunctionalized silicate layer, the first functionalized silicate layercomprising a tetrahedral silicate layer and a functional group, anoctahedral brucite layer, the octahedral brucite layer comprisingmagnesium oxide/hydroxide, and a second functionalized silicate layer,the second functionalized silicate layer comprising the tetrahedralsilicate layer and the functional group, where the octahedral brucitelayer is positioned between the first functionalized silicate layer andthe second functionalized silicate layer; and the functional group, thefunctional group covalently bonded to the tetrahedral silicate layer ofthe first functionalized silicate layer and separately covalently bondedto the tetrahedral silicate layer of the second functionalized silicatelayer, where the functional group extends from both the firstfunctionalized silicate layer and the second functionalized silicatelayer away from the octahedral brucite layer.
 2. The composition ofclaim 1, where a thickness of the synthetic layered magnesium silicateis 1 nanometer, where a lateral dimension of the synthetic layeredmagnesium silicate is between 2 nm and 5 microns.
 3. The composition ofclaim 1, where the functional group is selected from the groupconsisting of hydroxyl groups (—OH), saturated alkyl groups having theformula (—CH₂(CH₂)_(x)CH₃), where x is an integer between 0 and 18,phenyl groups, amine groups, diamine groups, carboxylate groups, amidegroups, acrylate groups, thiol groups, methacrylate groups, isocyanategroups, and combinations of the same.
 4. A method of using a syntheticfunctionalized additive in a well fluid, the method comprising the stepsof: preparing a well fluid, where the well fluid is selected fromaqueous-based fluids, oil-based fluids, and combinations of the same;adding an amount of the synthetic functionalized additive to the wellfluid to produce a rheologically-modified well fluid; subjecting therheologically-modified well fluid to a shear stress; and injecting therheologically-modified well fluid into a well.
 5. The method of claim 4,where the synthetic functionalized additive comprises a syntheticlayered magnesium silicate and a functional group, where the functionalgroup is covalently bonded to the synthetic layered magnesium silicate,where the functional group is selected from the group consisting ofhydroxyl groups (—OH), saturated alkyl groups having the formula(—CH₂(CH₂)_(x)CH₃), where x is an integer between 0 and 18, phenylgroups, amine groups, diamine groups, and combinations of the same. 6.The method of claim 4, where the amount of the synthetic functionalizedadditive in the rheologically-modified well fluid is between 0.1% w/v to20% w/v.
 7. The method of claim 4, where the rheologically-modified wellfluid is operable to exhibit rheologically-independent behavior.